Just hours earlier, the prime minister had denied reports of Mr. Bongo's death, declaring him "alive and well."

Shortly after announcing Mr. Bongo's death, Gabon's government declared it was closing the country's air, land and sea borders.

The Defense Ministry released a statement Monday saying that "all components" of Gabon's defense forces were being put in place. The statement, which was read on television, also called for citizens to increase their "vigilance and patriotism" during this "difficult" time.